This invention relates to metal plating. More particularly, it relates to a metal finish of a gold alloy and a method of plating to produce such finish.
Gold plating is currently accomplished by several techniques, including electrolytic plating, immersion plating, and autocatalytic plating (reduction of gold from gold solutions). Because of the rapid rise in gold prices, the plating industry is concentrating considerable effort in finding ways to produce metal finishes that exhibit the desirable properties of gold plating, including environmental aging, temperature and humidity cycling, handling, solderability, TC and ultrasonic weldability, cosmetic appearance and abrasion resistance. Among the substitute metal finishes which have been utilized are tin, nickel boron, tin nickel and tin lead films, to name a few. None of the foregoing have been found to substantially approximate the qualities of gold. Gold/nickel electroplating has also been employed, but such processes suffer from the disadvantage that control of the chemistry is difficult and electrical connection to the workpiece is required. Electroless gold alloy finishes have been prepared in an attempt to extend the amount of gold without sacrificing performance. For example, Japanese Pat. No. 33-7514, reports a gold/nickel alloy having 1.5 times the anti-abrasion properties of gold. However, the nickel to gold ratio is relatively low, at best only 15-20%, and thus the goal of significant cost savings is eluded.